The present invention relates to aerosol dispensing devices, and in particular to valve assemblies that provide automatic dispensing of chemical at predetermined time intervals, without requiring the use of electrical power.
Aerosol cans dispense a variety of ingredients. Typically, an active is mixed with a propellant which may be gaseous, liquid or a mixture of both (e.g. a propane/butane mix; carbon dioxide), and the mixture is stored under pressure in the aerosol can. The active mixture is then sprayed by pushing down/sideways on an activator button at the top of the can that controls a release valve. For purposes of this application, the term xe2x80x9cchemicalxe2x80x9d is used to mean liquid, liquid/gas, and/or gas content of the container (regardless of whether in emulsion state, single homogeneous phase, or multiple phase).
The pressure on the button is typically supplied by finger pressure. However, for fragrances, deodorizers, insecticides, and certain other actives which are sprayed directly into the air, it is sometimes desirable to periodically refresh the concentration of active in the air. While this can be done manually, there are situations where this is inconvenient. For example, when an insect repellant is being sprayed to protect a room overnight (instead of using a burnable mosquito coil), the consumer will not want to wake up in the middle of the night just to manually spray more repellant.
There a number of prior art systems for automatically distributing actives into the air at intermittent times. Most of these rely in some way on electrical power to activate or control the dispensing. Where electric power is required, the cost of the dispenser can be unnecessarily increased. Moreover, for some applications power requirements are so high that battery power is impractical. Where that is the case, the device can only be used where linkage to conventional power sources is possible.
Other systems discharge active intermittently and automatically from an aerosol can, without using electrical power. For example, U.S. Pat. No. 4,077,542 relies on a biased diaphragm to control bursts of aerosol gas at periodic intervals. See also U.S. Pat. Nos. 3,477,613 and 3,658,209.
However, biased diaphragm systems have suffered from reliability problems (e.g. clogging, leakage, uneven delivery). Moreover, they sometimes do not securely attach to the aerosol can.
Also, in some cases it is desirable to greatly restrict and carefully control the amount of aerosol being sprayed with each burst. Many of the systems developed to date do not adequately meet this need.
Thus, a need still exists for improved automated aerosol dispensers that do not require electrical power.
In one aspect the invention provides a dispenser that is suitable to dispense a chemical from an aerosol container. The dispenser is of the type that can automatically iterate between an accumulation phase where the chemical is received from the container, and a spray phase where the received chemical is automatically dispensed at intervals.
The dispenser has a housing mountable on an aerosol container, a movable diaphragm associated with the housing, the diaphragm being biased towards a first configuration, an accumulation chamber inside the housing for providing variable pressure against the diaphragm; and valving operable in response to movement of the diaphragm for controlling flow of the chemical from the aerosol container to the accumulation chamber, and from the accumulation chamber out the dispenser.
When the diaphragm is in the first configuration spray of the chemical out of the dispenser is prevented while flow of the chemical from the aerosol container to the accumulation chamber is permitted. When the pressure of chemical inside the accumulation chamber exceeds a specified threshold the diaphragm can move to a second configuration where chemical is permitted to spray from the dispenser.
There are four primary preferred embodiments. In a first of these, a first valve element is linked to the diaphragm to axially move therewith and control flow from the accumulation chamber out the dispenser via a first outlet path. There is also a second valve element that is linked to the diaphragm to axially move therewith and control flow from the aerosol container out the dispenser via a second outlet path that is separate from the first.
In a second of these a first valve element is linked to the diaphragm to axially move therewith and control direct flow from the aerosol container out the dispenser via a first outlet path. There is also a second valve element that is mounted adjacent the diaphragm to contact the diaphragm in the first configuration and not contact the diaphragm in the second configuration, the second valve element controlling flow from the accumulation chamber to the first outlet path.
In a third of these, a first valve element is linked to the diaphragm to axially move therewith and control flow from the accumulation chamber out the dispenser via a first outlet path. In this form, all chemical exiting the dispenser must pass through the accumulation chamber to exit the dispenser. This restricts each burst to a very small, consistent, controlled amount.
In the fourth of these, a first valve element is linked to the diaphragm to move therewith and control flow from the accumulation chamber out the dispenser via an outlet path. The chemical in the accumulation chamber exerts pressure against the diaphragm by exerting pressure against an intermediate transverse shuttle on which the first valve element is positioned.
Still other preferred forms of the invention provide a diaphragm that will shift back to the first configuration from the second configuration when pressure of the chemical in the accumulation chamber falls below a threshold amount. Typically, such a container is linked to the housing, and there is an actuator portion of the housing that rotates to allow chemical to be able to leave the container.
Alternatively, chemical flowing from the accumulation chamber can merge with chemical flowing from the aerosol container prior to exiting the dispenser, or can exit the dispenser as a separate stream from the chemical flowing directly out the dispenser from the aerosol container, when the diaphragm is in the second configuration.
Methods for using these dispensers with aerosol containers are also disclosed.
The present invention achieves a secure mounting of a dispensing valve assembly on an aerosol can, yet provides an actuator that has two modes. In one mode the valve assembly is operationally disconnected from the actuator valve of the aerosol container (a mode suitable for shipment or long-term storage). Another mode operationally links the valve assembly to the aerosol container interior, and begins the cycle of periodic and automatic dispensing of chemical there from. Importantly, periodic operation is achieved without requiring the use of electrical power to motivate or control the valve.
The valve assembly has few parts, and is inexpensive to manufacture and assemble. Further, it is self-cleaning to help avoid clogs and/or inconsistent bursts. Moreover, certain of these embodiments provide an extra degree of control over the volume of burst delivered in each spray. Others provide an extra degree of control by separating accumulation chamber pressures from a separate aerosol can outlet flow.
The foregoing and other advantages of the invention will appear from the following description. In the description reference is made to the accompanying drawings which form a part thereof, and in which there is shown by way of illustration, and not limitation, preferred embodiments of the invention. Such embodiments do not necessarily represent the full scope of the invention, and reference must therefore be made to the claims herein for interpreting the scope of the invention.